Quick test pull of the trim on the inside windscreen pillar on the side is not working,
Disconnect the two wire red and a brown connect a bulb across the two of them, turn you heated screen on if it lights up your wiring fuses and relay are good,
And your screen is toast
But to be honest if the screen has been changed before, the non original mini ones are not as thick as the genuine ones and you only need a few stone chips to mess up the heating element.
the element is very close to the surface on the non genuine ones :-( my one is trashed both sides needs replacing really
Hope this helps